Specific gravity - Wikipedia
Multiply the specific gravity by 1, to calculate the density of the substance in kilograms per cubic meter (kg/cubic meters) units. For example. An introduction to density, specific gravity and specific weight - formulas with Molecular weights can be used to calculate Specific Gravity if the densities of the . The relations between volume, pressure, temperature and quantity of a gas. Specific Gravity based on Molar Mass. This method is used to calculate the specific gravity from the molar mass. Specific Gravity is calculated as follows.
At low temperatures and pressures, the properties of equilibrium vapors and liquids are extremely different e. As the pressure and temperature are increased along the coexistence curves, liquid density, viscosity, and other properties generally decrease while vapor density and viscosity generally increase.
Thus, the difference in the physical properties of the coexisting phases decreases. These changes continue as the temperature and pressure are raised until a point is reached at which the properties of the equilibrium vapor and liquid become equal. The temperature, pressure, and volume at this point are called the "critical" values for that species.
- Specific Gravity based on Molar Mass
- Gas properties
Location C on Fig. The critical temperature and pressure are unique values for each species and are useful in correlating physical properties.
Specific Gravity based on Molar Mass
Critical constants for some of the commonly occurring hydrocarbons and other components of natural gas can be found in Table 1. Table 1 - Some physical constants of hydrocarbons.
However, slightly different standards are sometimes used in different locations and in different units. The ideal gas laws can be used to show that the specific gravity ratio of densities is also equal to the ratio of the molecular weights. By convention, specific gravities of all gases at all pressures are usually set equal to the ratio of the molecular weight of the gas to that of air Although specific gravity is still frequently used, this traditional term is not used under the SI system; it has been replaced by "relative density.
Analyses also can be expressed in terms of the volume, weight, or pressure fraction of each component present. Under limited conditions, where gaseous mixtures conform reasonably well to the ideal gas laws, the mole fraction can be shown to be equal to the volume fraction but not to the weight fraction. The apparent molecular weight of a gas mixture is equal to the sum of the mole fraction times the molecular weight of each component.
In modern laboratories precise measurements of specific gravity are made using oscillating U-tube meters. These are capable of measurement to 5 to 6 places beyond the decimal point and are used in the brewing, distilling, pharmaceutical, petroleum and other industries.
The vibrating fork immersion probe is another good example of this technology. This technology also includes many coriolis-type mass flow meters which are widely used in chemical and petroleum industry for high accuracy mass flow measurement and can be configured to also output density information based on the resonant frequency of the vibrating flow tubes. Ultrasonic transducer Ultrasonic waves are passed from a source, through the fluid of interest, and into a detector which measures the acoustic spectroscopy of the waves.
Fluid properties such as density and viscosity can be inferred from the spectrum. Radiation-based gauge Radiation is passed from a source, through the fluid of interest, and into a scintillation detector, or counter.
As the fluid density increases, the detected radiation "counts" will decrease.
How to Convert Specific Gravity in Weight | Sciencing
The source is typically the radioactive isotope cesiumwith a half-life of about 30 years. A key advantage for this technology is that the instrument is not required to be in contact with the fluid — typically the source and detector are mounted on the outside of tanks or piping. Since buoyancy force is linear with respect to the density of the liquid within which the float is submerged, the measure of the buoyancy force yields a measure of the density of the liquid.